Nuclear reactor

Abstract

In a water-cooled nuclear reactor for producing energy and having seed and blanket zones, which reactor is cooled by pressurized water and contains fissile material of plutonium and uranium, the reactor is provided, in its seed zones and blanket zones, with a plutonium composition such as obtained from light water power plant reactors after a normal service life and recycle, and with fuel elements whose geometry in the seed and blanket zones, with respect to the coolant water, is selected to produce an epithermal neutron spectrum.

What is claimed is: 
     
       1. An epithermal nuclear breeder reactor comprising an active core and means containing a body of pressurized water as a moderator for cooling said core, wherein: said core is composed of a plurality of unit subassemblies each composed of a seed region with moderator to fuel volume ratio of the order of 0.5 and a blanket region with moderator to fuel volume ratio of the order of 0.3, each said region comprising fuel rods of fissile and fertile materials; each said fuel rod in said region is composed of two parts which are configured and movable relative to one another in a manner to vary the number of neutrons leaking from said seed region into said blanket region; said fissile material comprises plutonium having an initial isotope composition such that the ratio of Pu 241  to Pu 239  is of the order of 30% and the ratio of Pu 240  to Pu 239  is of the order of 40%, said fertile material comprises U 238  ; said seed region contains plutonium in a concentration of 8 to 14%, by weight; and said blanket region contains plutonium in a concentration of 2 to 6%, by weight.